1. Field of the Invention
The invention discloses an apparatus and method for measuring olfactory threshold.
2. Background of the Art
The measurement of olfactory thresholds are beneficial in evaluating and managing a number of human conditions. Some of these are: damage to the olfactory nerves or olfactory bulb by head trauma; early detection of Alzheimer disease and Parkinson""s disease; damage due to acute viral and/or bacterial infections, e.g. HIV; damage to the olfactory system due to exposure to fumes and chemicals; side-effects from radiation therapy to the head; and others. A medical diagnostic instrument that can measure olfactory thresholds in an accurate mainer, quickly and at a lower cost is needed. This type of instrument could be used not only as a one time evaluation of a patient, but it could be used to trace a patient""s progress over time to monitor for onset of a particular occurrence.
The measurement of olfactory thresholds is accomplished today by various means. One method is by using scratch-and-sniff pads where the test operator scratches the surface to expose the odor, puts it up to the patient""s nose, and asks for a response. Different parts of the pad expose stronger and stronger odors. Another test method is using squeeze-bottle smell test kits. Here a series of bottles with increasing concentration of vapors is used. In both these methods the freshness of the samples and the skill of the test operator are critical factors in the test results. Obtaining good quantitative test results is difficult with these methods. Another method is the use of a large research-type olfactometer. The disadvantage to this method is that the test is slow and the cost of the instrument is very high. The present invention overcomes the disadvantages of the present methods.
The instrument described in this patent application was initially focused on Alzheimer and Parkinson disease, but can be applied to all of the above conditions and others that have similar degenerative effects on the region of the brain that controls olfactory response. The key component of the instrument is a jetting device that dispenses small, precise, known quantities of the odor causing fluid onto a heated surface which causes fluid to be vaporized and transported to the patient under test. Patent applications xe2x80x9cMethod and Apparatus for Delivery of Fragrances and Vapors to the Nosexe2x80x9d, Ser. No. 09/176,818 filed Oct. 22, 1998 and xe2x80x9cPresenting Airborne Material to the Nosexe2x80x9d, application Ser. No. 08/837,646 filed Apr. 21, 1997 are incorporated herein by reference.
The concentration of vapor molecules exposed to the nose of the person being tested is dependent on the number and size of the droplets deposited onto the heater surface. By varying the number of droplets and evaluating whether or not the patient smells the odor, the threshold can be determined accurately. Because the concentration of the vapor exposed to the nose is digitally controlled, the entire testing process can be run either automatically or under the control of a test operator. Sensors can be incorporated into the instrument to measure concentration of the vapors directly, to measure when the patient has sniffed, and the exact number of droplets dispensed. Each of these sensors improves the reliability of the testing and therefore can reduce the total test time required. These sensors also allow for self calibration of the instrument and a more operator independent test process.